I've got a MacBook Pro (revision 5,3) which was produced in the middle of 2009 and has 49 charge cycles. When it was all new, it showed a battery capacity of around 6500 mAh.
Now that I've been using it a few months (regularly on battery), the capacity dropped to 6400 mAh at 49 cycles.
Unfortunately I had have a little issue with the MacBook's sleep mode: it seems that if my battery gets low, I get a warning message, and about 10 minutes later it simply shuts down. What I find weird about this is that it's not entering sleep (until the battery is completely depleted), but it simply shuts down, and when I connect it to mains, it restores from the safe sleep (loads RAM from disk).
I tried resetting PRAM, SMC and also re-calibrated the battery. Any ideas?
Update:
The problem I see is the fact that the MacBook does not go to sleep when the battery is empty. My previous MacBooks went to sleep a while after the battery warning, keeping the RAM alive for a few hours before the battery gets completely empty, then shutting down (deep sleep/suspend to disk). During that time you could reconnect the power supply and the MacBook resumed from RAM instead of disk.
From Apple:
When the battery reaches "empty", the computer is forced into sleep mode. The battery actually keeps back a reserve beyond "empty", to maintain the computer in sleep for a period of time. Once the battery is truly exhausted, the computer is forced to shut down. At this point, with the safe sleep function introduced in the PowerBook G4 (15-inch Double-Layer SD) computers, the computer's memory contents have been saved to the hard drive. When power is restored, the computer returns itself to its pre-sleep state using the safe sleep image on the hard drive.
You see, the problem is that my MacBook does not go to sleep, instead is simply shuts down.
